1. Field of the Invention
This invention relates to spring scales and more particularly to that class adapted to weight containers carrying fluids.
2. Description of the Prior Art
The prior art abounds with spring scales apparatus useful in weighing a variety of objects. U.S. Pat. No. 479,718 issued on July 26, 1892 to F. H. Morgan, et al., teaches a pair of tubular bodies, one being slidably engaged within the other, being disposed at a preferred location relative one another by a spring, co-axially aligned with and contained within both tubular bodies. Extending the spring, such as by adding a weight to the inner tubular body, causes indicia carried by the inner tubular body, to become exposed. A port in the outer tubular body is provided with a sight line permitting the numerical indicia to indicate the weight of the object suspended by the innermost tubular body.
U.S. Pat. No. 3,107,745 issued on Oct. 22, 1963 to A. F. Dujan discloses a pair of triangularly shaped hollow elements disposed one within the other and secured together by a spring element extending between them. A vessel containing medicaments is suspended from below the innermost element having its weight measured by indicia carried by the innermost element, read through the transparent outermost element. A slide element, comprising a pair of pointers, is frictionally engaged with one apex of the outermost triangularly shaped element and is useful in determining the terminal desired weight of the liquid container suspended from the apparatus as well as intermediate weights.
Both of the aforementioned patents suffer the common deficiency of providing a single or at best a double sight line for measuring the weight of the suspended article, wherein the weight is expressed in units of volume or weight units. Furthermore, both apparatus fail to provide a vernier adjustment capable of compensating for the weight of a growing plant carried by a suspended container.